Alloy



Patented Dec. 23, 1924..

UNITE? STATES PATENT OFFICE.

ALLOY.

No Drawing.

To all whom it may concern:

Be it known that I, STUART EVAN MAC- Garcon, a subject of the King ofEngland, residing at Windsor, in the county of Essex, Province ofOntario, Canada, have invented certain new and useful Improvements inAlloys, of which the following is a specification.

This invention relates to alloys and it comprises as a new and usefulcomposition of matter, an alloy containing nickel, cobalt, chromium,tungsten and carbon.

The primary use of this alloy is for cutting tools for the machining ofcast iron and soft steel at a high rate of speed. It has alsobeen foundto beef great value. in turning alloy steels containing nickel,molybdenum, and other hardening'ingredients. It is especially valuablefor use with cast iron and steel articles where the surface is veryhard.

The alloy is non-magnetic, non-corrosive and is not readily attacked byany single acid. It will .not stain or tarnish under any conditions sofar observed. It will take a razor edge and maintain it better than anyother similar alloy now known.

The preferred composition of the alloy will consist of nickel about 14per cent, cobalt about 27 per cent, tungsten about 28 per cent, chromiumabout'31 per cent, and carbon about 1.25 per cent. An excellentmodification of this alloy has the following composition: Nickel about16 per cent, cobalt about 20 per cent, tungsten about 32 per cent,chromium about 32 per cent, and carbon about .98 per cent.

It will be obvious that the percentages of amounts of ingredients setforth in these examples may be varied within reasonable ranges whilemaintaining the same general characteristics of the alloys obtained inemploying such variations as obtained through the use of the percentagespresented in these examples.

The function of the nickel appears to be to produce a quality oftoughness highly de-. sirable in a cutting tool.

The cobalt has asimilar function to that of the nickel in producing thequality of toughness and it also seems to impart the quality ofresistance to heat so that the tool will maintain its cutting qualityeven when at a red heat.

Applicationfiled December 28, 1921. Serial N0. 525,521;

The nickel and cobalt may vary jointly any increase in the amount ofcobalt, being accompanied by a corresponding decrease in the amount ofnickel. The total ercentage of the nickel and cobalt jointly wi 1 notvary greatly from 0 per cent of the total amount.

The chromium has the function of imparting great hardness to the alloyand it is also an important factor in resistance to cor- IOSlOIl.

The tungsten has the function of increasing the resistance to heat andprobably also increasing the hardness of the alloy.

The carbon should not vary greatly from 1 per cent, except for certainspecial uses referred to later.

It is thought that the nickel, chromium and carbon unite to form adouble carbide of nickel and chromium which gives to the alloy itsextreme hardness as well as its fine grain and resistance to shock. Thealloy is thus probably composed of a solid solution in cobalt andtungsten of a carbide of nickel and chromium.

The alloy is made by melting the ingredients in a crucible in anelectric or oil furnace at a temperature of approximately 3600 F. Thecarbon is included by the addition of boron carbide. The nickel andcobalt are placed in the bottom of the crucible and the chromium placedin a layer over them. The tungsten mixed thoroughly with the requisiteamount of boron carbide is then placed upon the chromium and coveredwith a layer of broken glass.

Upon heating, the glass quickly melts and forms a protecting layer ofslag which prevents any loss of carbon and which also protects the hotmetal from the oxidizing effect of the air. Any oxides which may be inthe mix are removed by the boron. In practice very little, if any, ofthe boron remains in the finished alloy:

Certain types of arc furnaces may also be used for melting, but thosetypes which are directly to the path must beavoided. This alloy is verysensitive. to carbon and therefore anything that tends to make thecarbon content hard to control must be avoided.

The alloy should be poured at a heat of about 8600 F. or 200 F. abovethe melting point. It is very important that the heat of pouring becontrolled closely. The alloy should be poured as soon as possible aftermelting because upon standing the tungsten tends to separate and to forma semi-fluid mass at the bottom of the crucible.

The alloy should be poured into graphite molds. A small percentage ofcarbon is taken up by the metal from the graphite so that a casting isobtained with an extremely hard outer or cutting edge and yet with acenter sufficiently tough to withstand severe shocks.

For certain purposes, such as valves for acid-proof pumps, where anextremely hard outer edge is not of paramount importance, the melt maybe poured into sand molds. In such cases, however, the amount of carbonin the alloy may be increased as much as 75 per cent. With closesupervision, an alloy is obtained which is uniform in composition andproperties, and which is entirely free from blowholes which in othercutting alloys cause so much trouble.

It will be of course understood that the ingredients as obtained uponthe market will contain small percentages of other metals or non-metals,but the addition of these to the alloy in small percentages will not thetotal greatly afi'ect the qualities of the alloy and for certain usesthese additional ingredients may even be beneficial.

I claim i 1. An alloy containing nickel and halt, not varying, jointly,widely from 40 per cent of the total, each being present in substantialamount; chromium and tungsten, each not varying widely from 30 per centof and carbon, in appreciable amount.

2. An alloy containing'nickel about 14 per cent, cobalt about 27 percent, chromium about 31 per cent, tungsten about 28 per cent, and carbonabout 1.25' er cent.

3. An alloy in which. nickel and cobalt constitute about 40 per cent,chromium and tungsten each about 30 per cent, and carbon about 1 percent.

In testimony whereof I afiix my signature in presence of two witnesses.

STUART EVAN MACGREGOR. Witnesses:

ARTHUR MINNICK, CHARLES W. STAUFFIGER.

